Gasification is a process for converting carbonaceous materials into carbon monoxide and hydrogen by reacting the raw material at high temperatures with a limited but measured amount of oxygen and/or steam. The idea is to extract energy from different types of organic materials. If the biomass is naturally sufficiently oxygenated, then no oxygen and/or steam need be utilized in the gasification.
Biomass is an abundant and renewable resource, and the gasification process produces fuels and compositions that can be used in many industries. For instance, the resulting mixture of carbon monoxide and hydrogen gas that results from biomass gasification is known as synthesis gas or syngas. The syngas product can be a more efficient combustion source than the original biomass material. The syngas can be used as a synthetic fuel for the transportation, electrical production, or other industries. As another example, the chemical industry could employ gasification products such as olefins (e.g., propylene, ethylene, and the like) and aldehydes, such as formaldehyde, for polymeric materials.
While syngas can be used directly for energy production, syngas can also be used, via additional processing, to produce methanol and hydrogen or otherwise be converted via the Fischer-Tropsch process into a synthetic fuel, such as synthetic syndiesel. Alternatively, the Fischer-Tropsch process may be configured to produce a “syncrude” to be used as a refinery feed in the same manner as fossil crude oil. Gasification can also begin with materials that are not otherwise useful as fuels. For example, bio-/organic waste can be used as the feed material.
The amount of energy introduced to the gasification process is a major expense that subtracts from the net power production from the syngas. There is also an environmental impact to producing the required energy for gasification. Biomass gasification with optimization of syngas yield is an ongoing challenge that, if overcome, could enable efficient conversion of biomass carbon to syngas. Biomass gasification and combustion, overall, is a renewable energy that is potentially CO2— neutral. That is, biomass cultivation can remove the same amount of CO2 from the atmosphere as is emitted from gasification and combustion.
There is a need for improvements to the chemical biomass gasification process. Ideally, such improvements would improve bio-oil or gas yield (whichever is the desired end product) and reduce lignin content in the resulting product, and otherwise produce an improved gasification process for biomass. As much hydrogen should be stripped off the biomass to give H2, and as much carbon converted to CO, as possible. With an H2:CO mole ratio of 2:1 or greater, the syngas can comprise a feed stream into a Fischer-Tropsch reactor system for conversion to syncrudes that are either predominantly hydrocarbon or mixed alcohols based. Again, an advantage of fuels derived from biomass gasification is that they are carbon neutral and, therefore, are not a net contributor of CO2, a possible green house gas.